The problem: Your furnace is failing and must be replaced (most last 15 to 20 years).
The solution: Look for an Energy Star-certified model, which could cut power bills by more than $200 a year, according to the Environmental Protection Agency.
Then keep the whole HVAC system running efficiently by having it serviced annually and by changing the air filter every few months.
Residents who live in these 25 growing towns see their incomes go the furthest.
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